Failure to prevent Iran from developing nuclear weapons would be a "Neville Chamberlain moment" for President Barack Obama, famed attorney Alan Dershowitz charges in an exclusive interview with Newsmax.

It would mark a failure of negotiation along similar lines to those the pre-war British prime minister had in talks with Adolf Hitler in Munich in 1938.

Instead Dershowitz says the administration must keep pressure on Tehran while indicating a willingness to reduce sanctions only in exchange for real change in its nuclear policy and allowing international inspections.

The administration made a mistakeby allowing the reduction of sanctions to be discussed so early in the negotiations with the Iranians, he said.

"As things currently stand, we are emboldening the Iranians, not moving them towards making real concessions," Dershowitz, one of Israel's staunchest defenders in the United States said.

"It will allow them to buy time and it will increase the prospect of actually having to go to war. It’s a bad negotiating tactic … this is a teacher giving his students a C- in negotiation skills. Everyone who teaches negotiation would say you don’t weaken your position in exchange for a promise of doing nothing. And that’s essentially what we're doing."

Dershowitz said if the mullahs are allowed to build nuclear weapons it would lead to a dangerous escalation which could threaten the world. "Saudi Arabia will want to develop or buy nuclear weapons."

"We're then going to see Iran trying to develop intercontinental ballistic missiles that could threaten not only southern Europe but ultimately all of Europe and perhaps even the eastern coast of the United States.

"If Iran develops nuclear weapons this will be the Neville Chamberlain moment for this administration," he said.

Chamberlain famously returned to London from talks with Hitler in Munich in September, 1938 with a signed agreement, which he said promised "Peace in our time." It allowed Germany to annex part of Czechoslovakia. Within a year World War II had broken out.

Dershowitz said the Obama administration has "spoken with two voices right from the beginning" with regard to its policy on Iran and nuclear weapons.

"There are those who were prepared to have containment and those — like the president — who said 'no, containment is off the table,' the military option is on the table," he said in the exclusive interview.

"If the choice comes down to Iran having a nuclear weapon or a preventive military attack . . . a preventive military attack is 'less bad' than allowing Iran to develop weapons and hope that they will be contained the way North Korea has been contained.

"Iran and north Korea are very, very different vultures."

He said the negotiating tactics have been bad, not only for countries such as Israel, France, Italy and Saudi Arabia, but for the United States too.

"It shows extraordinary weakness. President Obama backed down from enforcing his read line on Syria, and now he's backing down it seems from keeping up the sanctions.

Remember, he tried to persuade Prime Minister Netanyahu not to attack Iran, saying we were going to keep the pressure on them through sanctions."

"Now — at the first opportunity — perhaps to enter into diplomacy, we're reducing the sanctions and that's a big mistake."

"It will mark the most dreadful failure. It will also mark the break of a promise directly by the president of the United States to the public, to me — to my face — to the Prime Minister of Israel and to many others.

"The president has promised that Iran will not be permitted to develop nuclear weapons. We certainly expect him to keep that promise."

Failure to prevent Iran from developing nuclear weapons would be a "Neville Chamberlain moment" for President Barack Obama, famed attorney Alan Dershowitz charges in an exclusive interview with Newsmax.